1. Field of the Invention
In general, the present invention relates to counterbalance systems for windows that prevent open window sashes from moving under the force of their own weight. More particularly, the present invention system relates to the brake shoe component of the counterbalance systems for tilt-in windows and the devices that activate the brake shoe component.
2. Description of the Prior Art
There are many types and styles of windows. One of the most common types of windows is the double-hung window. Double-hung windows are the window of choice for most home construction. A double-hung window consists of an upper window sash and a lower window sash. Either the upper window sash or the lower window sash can be selectively opened and closed by a person sliding the sash up and down within the window frame.
A popular variation of the double-hung window is the tilt-in, double-hung window. Tilt-in, double-hung windows have sashes that can be selectively moved up and down. Additionally, the sashes can be selectively tilted into the home so that the exterior of the sashes can be cleaned from within the home.
The sash of a double-hung window has a weight that depends upon the materials used to make the window sash and the size of the window sash. Since the sashes of a double-hung window are free to move up and down within the frame of a window, some counterbalancing system must be used to prevent the window sashes from always moving to the bottom of the window frame under the force of their own weight.
For many years, counterbalance weights were hung next to the window frame in weight wells. The weights were attached to the window sash using a string or chain that passed over a pulley at the top of the window frame. The weights counterbalanced the weight of the window sashes. As such, when the sashes were moved within the window frame, they had a neutral weight and friction would hold them in place.
The use of weight wells, however, prevents insulation from being packed tightly around a window frame. Furthermore, the use of counterbalance weights on chains or strings cannot be adapted well to tilt-in, double-hung windows. Accordingly, as tilt-in windows were being developed, alternative counterbalance systems were developed that were contained within the confines of the window frame and did not interfere with the tilt action of the tilt-in windows.
Modern tilt-in, double-hung windows are primarily manufactured in one of two ways. There are vinyl frame windows and wooden frame windows. In the window manufacturing industry, different types of counterbalance systems are traditionally used for vinyl frame windows and for wooden frame windows. The present invention is mainly concerned with the structure of vinyl frame windows. As such, the prior art concerning vinyl frame windows is herein addressed.
Vinyl frame, tilt-in, double-hung windows are typically manufactured with guide tracks along the inside of the window frame. Brake shoe assemblies, commonly known as “shoes” in the window industry, are placed in the guide tracks and ride up and down within the guide tracks. Each sash of the window has two tilt pins or tilt posts that extend into the shoes and cause the shoes to ride up and down in the guide tracks as the window sashes are opened or closed.
In prior art counterbalance systems, the shoes serve more than one purpose. The shoes contain a brake mechanism that is activated by the tilt post of the window sash when the window sash is tilted inwardly away from the window frame. The shoe, therefore, locks the tilt post in place and prevents the base of the sash from moving up or down in the window frame once the sash is tilted open. Second, the shoes engage coil springs. Coil springs are constant force coil springs that supply the counterbalance force to the weight of the window sash.
Single coil springs are used on windows with light sashes. Multiple coil springs are used on windows with heavy sashes. The coil springs provide the counterbalance force to the window sashes needed to maintain the sashes in place. The counterbalance force of the coil springs is transferred to the window sash through the structure of the shoes and the tilt posts that extend from the window sash into the shoes.
Prior art shoes that contain braking mechanisms and engage counterbalance coil springs are exemplified by U.S. Pat. No. 6,378,169 to Batten, entitled Mounting Arrangement For Constant Force Spring Balance.
There are many state and municipal building code statutes that affect the design of windows. For instance, building codes require that all bedrooms in a home be accessible by at least one window. Furthermore, bedroom windows must be of a size large enough for a person to pass through the window in case of a fire. The size regulated by the statute is not the size of the windowpane, but rather the size of the opening presented by a window when the sash is fully open. In modern tilt-in windows, the springs of the counterbalance system are stored in the window tracks. The presence of the counterbalance system prevents a window sash from opening fully. Due to the interfering components, the maximum opening provided by a window is always a few inches smaller than the height of the window sash. Consequently, in order to meet the building code requirements for an acceptable access opening, the windows must have sashes a few inches larger than that required opening. In other words, the window must be oversized. However, the larger a window is, the larger the counterbalance system that is required and the greater the chance that a child can tumble out of a window.
Since bedroom windows may need to be used as an escape during a fire, the windows cannot contain bars or other features that would prevent a person from inadvertently passing through the window. Although such building code statutes are intended to make homes safer, such statutes create other safety problems.
Each year, many small children are injured or killed by falling out of open windows. The accidents increase as windows are designed to become easier and easier to open. Since building codes prevent windows from being manufactured with obstructions, many parents attach aftermarket bars to windows. The aftermarket bars prevent a child from falling from the window. However, the bars also prevent a child from a window in the event of a fire. Furthermore, many aftermarket safety bars prevent a tilt-in window from tilting inwardly for cleaning.
A great need therefore exists for a new window design that can present a larger access opening without requiring a larger sash size. A need also exists for a counterbalance system that enables unobstructed access to a window during a fire, yet deters a child from accidentally opening a window and falling out. These needs are met by the present invention as described and claimed below.